Agricultural machines, such as tomato harvesters, have in the past had to rely to a distressing degree upon the skill of the machine operator. Some machine operators were extremely experienced and capable and were able to produce a good yield of tomatoes, but other operators, less experienced or less particular, failed to recover a large proportion of the tomatoes to be harvested. Also, we have found that even careful and capable operators have been under strain while operating the harvester and that this has often required rest stops, or else deterioration in the quality of the operation.
It is, of course, extremely desirable that the machine be less dependent upon the skill and experience of the operator. Therefore, it is an object of the present invention to enable an approximately maximum result even with an inexperienced operator. This is accomplished by providing a tomato harvester in which the severing sickle or blade is automatically controlled so that it always operates at the desired optimum position to which it is set.
Again, even an experienced operator has some difficulty in determining the depth at which the blade is operating, especially when the blade or sickle is somewhat underground. It is remarkable that these operators have been able to do as well as they have done, since their vision has been obscured by the tomato plants that were being cut and transported from the severing sickle up an elevator to the shaker.
With the present invention, the blade is automatically kept in the position where the operator would desire it to be, so that the operator basically needs only to steer the machine accurately and to regulate its forward speed. These two things are relatively easly to do, and to do properly.
A surprising result of the invention is that the tomato harvest is substantially increased while the strain on the operator is reduced and while enabling nearly anyone who can properly control a tractor to be a good operator, for with this invention nearly anyone can learn to be a good harvester operator, usually in just a few minutes. About all the operator needs to do, other than to steer and regulate the speed of the vehicle, is to lift the sickle device out of the ground at the end of each row by an uncritical amount, turn the machine around and align it with the next row to be harvested, for then the harvester, when actuated to do so, automatically relocates the blade at the proper depth.
Another surprising result of the invention is that it reduces the amount of dirt picked up by the harvester during harvesting. It has been found that when the sickle is kept at the proper depth, the number of clods of dirt sent up the elevator is drastically reduced. Moreover, the sickle blade can be so accurately controlled that it can be operated somewhat higher than heretofore and yet produce very successful results; as a result of this higher position less dirt is lifted toward and upon the pick-up portion of the harvester, yet the number of tomatoes recovered is not substantially less, if any less.
When a harvester sickle or blade is cutting underground, it produces a ground swell which, when observed underneath the harvester, appears as a ground wave traveling with the tractor, so that with respect to the tractor it is substantially a standing wave. The dirt, as viewed with respect to the field, is lifted above ground and then settles back onto it and into it at a level slightly higher than before it was disturbed. It is very important in operating a tomato harvester to make sure that the cutting blade does not begin to get gradually deeper, because, if it does, it tends very soon to produce a kind of action in which the blade dives into the ground and thereby stops completely the operation of the harvester. This blade-diving is one trouble that inexperienced operators have heretofore had. In order to avoid this, a cautious operator may sometimes operate with the blade too shallow, thereby losing many of the tomatoes that should be recovered.
In maintaining the desired depth it is, of course, important that the actual depth at which the blade is operating (or its height aboveground where that would be desirable) be continually known, so that the controls which govern blade or sickle placement can respond by comparing that actual position with the desired position and can bring the two into consonance. Another object of the invention is to enable this to be done.
Another extremely desirable result, which has been achieved by the invention, is that the harvester can be operated in fields in which there has been a recent rain, at least in fields where the rain has not made the soil into mud for any substantial depth. As long as the mud is only at or near the surface, the present machine can operate without bringing mud in significant amounts up onto the harvester's elevator.
It is important that mud and dirt not pass through the harvester and into the collected tomatoes, because the buyers (canners, where the crops are grown for canning) pay a much lower price per ton of tomatoes when the tomatoes are covered with mud and also when a substantial portion of the load is dirt or mud. Dirt in the load not only reduces the weight of tomatoes compared with the total weight, but also necessitates cleaning the tomatoes; mud makes the situation even worse. Therefore, growers are very eager to keep the harvested tomatoes clean. Heretofore this has usually meant not harvesting if the field was even slightly muddy and has required expensive devices to control the flow of dry dirt. The depth-control device of this invention, which costs about the same as do the devices controlling dirt flow, can be used either with or without the dirt control device. Considerable money can be saved when the purchaser need not buy any dirt control device, as he need not when using the harvester of this invention.